Vehicular crash testing is sometimes done by crashing vehicles into a barrier. Dummies are often placed within the interior of such vehicles in order to test safety equipment and determine the effect of such crashes on the occupants of a vehicle. The result of such crash testing is that the vehicles themselves are damaged.
As an alternative to testing vehicles by crashing them into barriers, sled testing systems are alternatively used where a portion of the vehicle, such as the interior or an interior component, may be subjected to accelerative forces similar to those which would be experienced during a crash. Like full vehicle testing, dummies may be placed within the interior or interior components of the vehicle being tested in order to test safety equipment, such as passenger restraints or cushioning, and determine the effect of a crash on the occupants.
Typically, the portion of the vehicle being tested, such as the interior, is mounted on a sled carriage which in turn is slidably mounted onto rails. A pneumatically or hydraulically driven piston is typically employed to drive the sled carriage in an accelerative manner such that the vehicle interior or other vehicle portion is accelerated at a rate similar to that experienced during a collision. The pneumatically or hydraulic driven piston, or driver member, typically includes a mechanism in order to control the acceleration of the sled carriage at various points along its path of travel. For example, in the case of a pneumatically driven system, a metering pin is often connected to one end of the pneumatically driven piston which in turn is slidably housed within a pneumatic tube. The metering pin is located between a load or high pressure chamber and a set or low pressure chamber within the pneumatic tube in order to control and regulate the acceleration. Such mechanisms for controlling acceleration rates, such as metering pins, and the overall driving mechanisms, such as pneumatic tube assemblies, are well known in the art and will not be discussed in further detail.
A problem with such typical sled testing systems is that the entire vehicle portion being tested is accelerated at the same rate. In actual collisions, the exterior portion of the vehicle being impacted is accelerated at one rate and is deformed so as to absorb some of the impact before that impact force is transmitted to accelerate other portions of the vehicle. In other words, different portions of the vehicle are accelerated at different rates.
In a more specific example, if a vehicle is impacted from the side, the door panel or panels of the vehicle being impacted will accelerate at one rate while absorbing some of the impact force in the form of door panel deformation. Because the door panel or panels will deform inwardly to some extent before the impact is transmitted to the remainder of the vehicle, the remainder of the vehicle will be accelerated at a different rate than the door panels. Accordingly, a typical sled testing system will not provide an accurate representation of the manner in which exterior body panels, such as door panels, will effect occupants of the vehicle interior or interior components being tested.
In an effort to more accurately simulate collisions, such as side collisions, sled testing systems have been employed in which a vehicle interior portion and an exterior panel, such as a side door panel, are mounted relative to one another onto one vehicle sled carriage so as to simulate their relative positions when assembled as components of a vehicle. A second impacter sled carriage is then driven into the side panel of the vehicle being tested such that the side panel being impacted is accelerated at one rate and is deformed so as to absorb some of the impact before that impact force is transmitted to accelerate the vehicle sled carriage and, accordingly, the vehicle interior portion.
While such sled testing systems using two movable carriages movably mounted upon the same platform have been used, an alternative system has been employed in the past where the vehicle carriage carrying a vehicle interior portion and an exterior panel is movably mounted on the impacter carriage which has an impacter structure. When the impacter carriage is forcibly accelerated, the impacter carriage will be acceleratingly moved relative to the vehicle carriage such that the exterior panel, such as a door panel, will be impacted by the impacter structure of the impacter carriage. The exterior panel will then deform so as to absorb some of the impact before the impact force is transmitted to accelerate the vehicle carriage and, accordingly, the vehicle interior portion.
However, there is a problem with both variations of the last system described. Because the acceleration of the vehicle carriage will be dependent upon the impact with, and absorption of the impact by, the exterior panel mounted on the vehicle carriage, the vehicle carriage acceleration cannot be controlled accurately and tests performed with such systems cannot be accurately controlled or repeated.